Histochemical evaluation of glutathione in brain

Glutathione (GSH) is a ubiquitous cellular sulfhydryl compound with a variety of essential functions. A histochemical method that was developed by others for the localization of GSH in tissue sections was used to study the localization of GSH in rodent and primate brain. Sections of freshly frozen tissue were stained for 4 min with Mercury orange dissolved in toluene, and viewed by fluorescence microscopy for the product of the reaction with soluble sulfhydryl compounds. Soluble sulfhydryl compounds are comprised almost exclusively of GSH. Although the brain exhibits strong staining characteristics, reflecting the millimolar levels of GSH that are detected by chemical assay, very little stain is seen in neuronal somata. Pretreatment of animals with diethyl maleate resulted in depletion of GSH from brain (measured by high performance liquid chromatography), as well as decreased Mercury orange staining. The staining pattern observed in the brain may indicate that GSH is primarily localized to non-neuronal elements, such as glia, and/or in axons and nerve terminals.